Risk Factors for Metastasis at Initial Diagnosis With Ewing Sarcoma

Purpose: We aimed to identify potential risk factors predictive of metastasis at initial diagnosis in Ewing sarcoma patients. Patients and methods: We enrolled selected patients diagnosed with Ewing sarcoma between 2004 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) Program database. Demographic and clinical features of patients were analyzed to demonstrate the potential risk factors of distant metastasis at presentation. We utilized descriptive statistics, univariate methods, and a series of regression models to analyze the significance of risk factors. Moreover, we conducted survival analysis in patients with different metastatic sites through Kaplan–Meier analysis. Results: We identified 1,066 cases of Ewing sarcoma and 332 (31.1%) of the patients had metastasis at initial diagnosis. In the univariate logistic regression analysis, patients had higher probability of metastasis at initial diagnosis if they aged between 18 and 59 years old (OR = 1.43; 95% CI, 1.09 to 1.86), had a tumor located in the axial or cranial bones (OR = 1.38; 95% CI, 1.05 to 1.81), or had a tumor over 8 cm (OR = 2.55; 95% CI, 1.66 to 3.89). These three factors were still significant when analyzed in a multivariate logistic regression model or another multivariate logistic regression model controlling for age, location, and tumor size, which had univariate p < 0.1. Besides, we found that patients with lung metastasis alone had a better prognosis than patients with bone metastasis alone or with two or more metastatic sites (p < 0.01). Conclusion: Ewing sarcoma patients with an age between 18 and 59 years old, a tumor in the axial or cranial bones, and a tumor size over 8 cm had an increased likelihood to have metastatic diseases at initial diagnosis.